Structure For adjusting inside Circumference of Helmet

ABSTRACT

A structure for adjusting inside circumference of a helmet is implemented as a strap assembly coupled to a rear side of a safety helmet or bicycle helmet and includes a casing and a cover fitted therein. The cover is sequentially connected with a transmission gear, a resilient element, a positioning gear and a knob. By pressing the knob, the positioning gear is disengaged from toothed portions on an inner periphery of the cover, thereby allowing the knob to rotate an end of the transmission gear. Consequently, a first driving portion of the transmission gear drives two straps inserted in the casing to move toward or away from each other. The knob is released after a relative position of the straps is adjusted. The resilient element returns the positioning gear into engagement with the toothed portions on the inner periphery of the cover.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a structure for adjusting an inside circumference of a helmet, and more particularly, to a strap assembly that is coupled to a safety helmet or a bicycle helmet and allows secure, flexible and rapid adjustment of a relative position of straps so as to match an inside circumference of the helmet with a user's head size.

2. Description of Related Art

Strap-adjusting assemblies of existing safety helmets come in a variety of configurations to adapt to different head shapes, and allow convenient adjustment of strap length. Two conventional strap assemblies for use with safety helmets are described below for example. Referring to FIG. 1, a first conventional strap-adjusting structure includes a knob 10, two straps 20, a casing 30, a cover 40, a positioning gear 50, a resilient element 503, a transmission gear 504 and a washer 505. During assembly of this strap-adjusting structure, the knob 10 is placed into the casing 30 before the positioning gear 50 is put into the knob 10, so that bevel teeth 501 on an outer side of the positioning gear 50 and teeth 502 on an outer periphery of the positioning gear 50 mesh respectively with bevel teeth 101 on an inner side of the knob 10 and projections 301 at an outer end of an inner periphery of the casing 30. Then, the resilient element 503 and the washer 505 are sequentially put in place, wherein the washer 505 is located in a groove on an inner side of the casing 30. Next, the two straps 20 are put in place in an overlapping manner and inserted by the transmission gear 504, allowing a resilient fastener 102 at an inner end of the knob 10 to retain the transmission gear 504. Finally, the cover 40 is securely connected with the casing 30, thereby completing the first conventional strap-adjusting structure.

A second conventional strap-adjusting structure is shown in FIGS. 2 and 3 and includes a knob 60 having an inner side annularly provided with bevel teeth 601. A gear 602 is protrudingly provided at a center of the bevel teeth 601 for meshing with teeth 901 alternately provided on an upper edge and a lower edge of slots formed respectively in two straps 90, wherein the toothed slots jointly form a toothed groove. In addition, a casing 70 has an outer side formed with an axle seat 701 at an appropriate position. The axle seat 701 includes an outwardly extending engaging portion 702 provided bilaterally with projections 703. The engaging portion 702 can be fitted into the inner side of the knob 60, so that the knob 60 is pivotable on the axle seat 701 while the projections 703 on the engaging portion 702 are engaged with the bevel teeth 601 on the inner side of the knob 60. A cover 80 is protrudingly provided with a resilient fastener 801 corresponding in position to a through hole 704 in the axle seat 701 of the casing 70. Thus, a central hole 603 of the knob 60 is retained by and pivotable on the resilient fastener 801 of the cover 80.

The knob 60, the casing 70 and the cover 80 are made of a plastic material. Therefore, a user only has to press and rotate the knob 60 for driving the projections 703 of the engaging portion 702 out of engagement with the bevel teeth 601 on the inner side of the knob 60, while simultaneously driving the straps 90 meshed with the gear 602 of the knob 60 to move toward or away from each other, thereby adjusting a combined length of the straps 90.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a novel configuration of a strap-adjusting assembly for use with a safety helmet or a bicycle helmet, with the hope that straps of a helmet can be conveniently and stably retained in place after strap length adjustment, so as to the secure the adjusted strap length.

A primary objective of the present invention is to provide a strap assembly coupled to a rear side of a safety helmet or a bicycle helmet. Therein, a casing is bilaterally provided with apertures that allow two ends of a matching cover to be fitted therein. The cover is centrally formed with a protruding section having a central hole and an inner periphery bilaterally provided with toothed portions. A first driving portion on an inner side of a transmission gear can penetrate the hole of the cover so as to mesh with toothed portions alternately provided on an upper edge and a lower edge of slots formed respectively in two straps inserted into the apertures of the casing. A tubular section centrally and protrudingly formed on the casing can penetrate a hole centrally formed in the transmission gear. A second driving portion on an outer side of the transmission gear can be inserted into a resilient element and engaged with inner teeth centrally formed on a positioning gear. The positioning gear has an outer periphery formed with teeth for meshing with the toothed portions on the inner periphery of the protruding section of the cover. A knob penetrable by a threaded fastener and having an inner side formed with inner teeth is disposed adjacent to a side of the positioning gear, so that the threaded fastener passing through the knob is securely connected with the tubular section of the casing that penetrates the transmission gear. By pressing the knob, the positioning gear is driven out of engagement with the toothed portions on the inner periphery of the protruding section of the cover, thereby allowing the knob to rotate an end of the transmission gear. Thus, the first driving portion on the inner side of the transmission gear can drive the two straps inserted in the casing to move toward or away from each other in a predetermined manner. The knob is released after a relative position of the straps is adjusted, so that the resilient element pushes the positioning gear outward to its original position, in which the positioning gear is engaged with and securely retained by the toothed portions on the inner periphery of the protruding section of the cover.

A secondary objective of the present invention is to provide the toothed portions on the inner periphery of the protruding section of the cover with chamfered inner edges, which are facing inward of the strap assembly, and to provide the teeth on the outer periphery of the positioning gear that mesh with the toothed portions on the inner periphery of the protruding section of the cover with chamfered outer edges, which are facing outward of the strap assembly, so that the positioning gear can be smoothly disengaged from or re-engaged with the toothed portions on the inner periphery of the protruding section of the cover.

A tertiary objective of the present invention is to provide the second driving portion on the outer side of the transmission gear with an unchamfered outer edge, which is facing outward of the strap assembly, and to provide the inner teeth on the inner side of the knob disposed adjacent to the side of the positioning gear with unchamfered inner edges, which are facing inward of the strap assembly, so that the second driving portion of the transmission gear cannot easily enter in between the inner teeth of the knob. Thus, a relative position of the transmission gear and the two straps can be secured.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The invention as well as a preferred mode of use, further objectives and advantages thereof will be best understood by referring to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:

FIG. 1 is an exploded perspective view of a first conventional strap assembly;

FIG. 2 is an exploded perspective view of a second conventional strap assembly;

FIG. 3 is an exploded perspective view of the second conventional strap assembly from another viewing angle;

FIG. 4 is a schematic drawing showing a strap assembly according to the present invention coupled to a helmet;

FIG. 5 is an exploded perspective view of the strap assembly according to the present invention;

FIG. 6 is a plane view of the strap assembly according to the present invention;

FIG. 7 is a cross-sectional view taken along a line 70-70 in FIG. 6;

FIG. 8 is a cross-sectional top view of the strap assembly according to the present invention when not in operation; and

FIG. 9 is a cross-sectional view taken along a line 90-90 in FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 5 and 8, a structure for adjusting an inside circumference of a helmet is implemented as a strap assembly 8 coupled to a rear side of a safety helmet or bicycle helmet 9. The strap assembly 8 comprises a casing 1, a cover 2, two straps 3, a transmission gear 4, a resilient element 5, a positioning gear 6, a knob 7 and a threaded fastener 73.

The casing 1 is bilaterally provided with apertures 11 and is centrally and protrudingly formed with a tubular section 12. In addition, the casing 1 has an inner side connected with a pad 13.

The cover 2 is a covering element shaped according to a width of the casing 1 and has two ends each formed as a reduced insertion end 21. Moreover, the cover 2 is centrally formed with an outwardly extending protruding section 22, which has a central through hole 24 and an inner periphery bilaterally provided with toothed portions 23.

Each of the two straps 3 has one end formed with a slot 31, wherein toothed portions 32 are provided alternately on an upper edge and a lower edge of one and the other of the slots 31.

The transmission gear 4 has an inner side formed with a first driving portion 41 and an outer side formed with an outwardly extending second driving portion 43, wherein the two sides are divided by a middle section formed with a flange 42. Besides, the transmission gear 4 is centrally provided with a hole 44.

The resilient element 5 can be inserted by the second driving portion 43 of the transmission gear 4.

The positioning gear 6 has an inner side concavely formed with an accommodating space 61 for receiving an end of the resilient element 5. Furthermore, the positioning gear 6 is centrally provided with inner teeth 62 for engaging with the second driving portion 43 of the transmission gear 4. The positioning gear 6 also has an outer periphery formed with teeth 63, which can mesh with the toothed portions 23 on the inner periphery of the protruding section 22 of the cover 2.

The knob 7 has an inner side formed with inner teeth 71 and an outer side formed with a through hole 72 for insertion by the threaded fastener 73.

Referring to FIGS. 8 and 9, in order to assemble the casing 1, the cover 2, the two straps 3, the transmission gear 4, the resilient element 5, the positioning gear 6, the knob 7 and the threaded fastener 73, the insertion ends 21 at the two ends of the cover 2 are fitted into the apertures 11 bilaterally provided on the casing 1. The first driving portion 41 on the inner side of the transmission gear 4 is inserted into the hole 24 of the cover 2, so as to mesh with the toothed portions 32 provided alternately on the upper edge and the lower edge of one and the other of the slots 31 of the two straps 3, which are inserted into the apertures 11 formed bilaterally on the casing 1, as shown in FIG. 6. The second driving portion 43 on the outer side of the transmission gear 4 is inserted into the resilient element 5 and engaged with the inner teeth 62 centrally formed on the positioning gear 6, as shown in FIG. 8. Meanwhile, the teeth 63 on the outer periphery of the positioning gear 6 mesh with the tooth portions 23 on the inner periphery of the protruding section 22 of the cover 2, as shown in FIG. 9. Afterward, the knob 7 is penetrated with the threaded fastener 73 and placed adjacent to a side of the positioning gear 6, so that the threaded fastener 73 is securely connected with the tubular section 12 of the casing 1 that passes through the transmission gear 4, thereby completing the strap assembly 8 shown in FIG. 4.

Referring now to FIGS. 6 and 7, when it is desired to adjust the strap assembly 8 so as to change a relative position of the straps 3, the knob 7 is pressed to drive the positioning gear 6 out of engagement with the toothed portions 23 on the inner periphery of the protruding section 22 of the cover 2, as shown in FIG. 7. Then, the knob 7 is turned to rotate the second driving portion 43 of the transmission gear 4, allowing the first driving portion 41 on the inner side of the transmission gear 4 to drive the two straps 3 inserted in the casing I to move toward or away from each other in a predetermined manner, as shown in FIG. 6. After the relative position of the two straps 3 is adjusted, the knob 7 is released, allowing the resilient element 5 to push the positioning gear 6 outward to its original position, as shown in FIG. 8, in which the positioning gear 6 once again meshes with and is retained by the toothed portions 23 on the inner periphery of the protruding section 22 of the cover 2.

As shown in FIG. 7, the toothed portions 23 on the inner periphery of the protruding section 22 of the cover 2 have inner edges formed with chamfers 231, wherein the inner edges are facing inward of the strap assembly 8. Meanwhile, the teeth 63 on the outer periphery of the positioning gear 6 that mesh with the toothed portions 23 have outer edges formed with chamfers 631, wherein the outer edges are facing outward of the strap assembly 8. Thus, the positioning gear 6 can be smoothly disengaged from and re-engaged with the toothed portions 23 on the inner periphery of the protruding section 22 of the cover 2.

On the other hand, the second driving portion 43 on the outer side of the transmission gear 4 has an unchamfered outer edge, which is facing outward of the strap assembly 8, while the inner teeth 71 on the inner side of the knob 7 have unchamfered inner edges, which are facing inward of the strap assembly 8, as shown in FIG. 8, so that the second driving portion 43 of the transmission gear 4 cannot easily enter in between the inner teeth 71 of the knob 7. Thus, a relative position of the transmission gear 4 and the two straps 3 can be secured. 

1. A structure for adjusting an inside circumference of a helmet, implemented as a strap assembly coupled to a rear side of a safety helmet or a bicycle helmet and comprising a casing bilaterally provided with apertures which can be passed through by two straps, respectively, and be fitted in by two ends of a cover centrally formed with a hole, so that driving components and a knob for adjusting a relative position of the two straps can be assembled with the casing and the cover, the structure being characterized in: the cover fitted in the casing being centrally formed with a protruding section having the hole and an inner periphery bilaterally provided with toothed portions, so that a first driving portion formed on an inner side of a transmission gear can penetrate the hole of the cover while a tubular section centrally and protrudingly formed on the casing can penetrate a hole centrally formed on the transmission gear; the transmission gear further having an outer side formed with a second driving portion which can be inserted into a resilient element and engaged with a positioning gear centrally formed with inner teeth, wherein the positioning gear has an outer periphery formed with teeth which can mesh with the toothed portions on the inner periphery of the protruding section of the cover; and the knob having an inner side formed with inner teeth and being penetrable by a threaded fastener, wherein the knob is disposed adjacent to a side of the positioning gear, so that the threaded fastener passing through the knob can be securely connected with the tubular section of the casing that passes through the transmission gear; wherein the knob can be pressed to drive the positioning gear out of engagement with the toothed portions on the inner periphery of the protruding section of the cover, allowing an end of the transmission gear to be rotated by the knob, so that the first driving portion formed on the inner side of the transmission gear drives the two straps inserted in the casing to move toward or away from each other in a predetermined manner, and wherein the knob can be released after the relative position of the two straps is adjusted, allowing the resilient element to push the positioning gear outward to its original position, in which the positioning gear once again meshes with and is retained by the toothed portions on the inner periphery of the protruding section of the cover.
 2. The structure for adjusting the inside circumference of the helmet as claimed in claim 1, wherein the toothed portions on the inner periphery of the protruding section of the cover have chamfered inner edges, which are facing inward of the strap assembly, while the teeth on the outer periphery of the positioning gear that mesh with the toothed portions on the inner periphery of the protruding section of the cover have chamfered outer edges, which are facing outward of the strap assembly, thereby allowing the positioning gear to be smoothly disengaged 15 from and reengaged with the toothed portions on the inner periphery of the protruding section of the cover.
 3. The structure for adjusting the inside circumference of the helmet as claimed in claim 1, wherein the second driving portion on the outer side of the transmission gear has an unchamfered outer edge, which is facing outward of the strap assembly, while the inner teeth on the inner side of the knob have unchamfered inner edges, which are facing inward of the strap assembly, so that the second driving portion of the transmission gear cannot easily enter in between the inner teeth of the knob, thereby securing a relative position of the transmission gear and the two straps. 